Endoscopes are used today for a number of applications in medicine and technology. Endoscopes typically include a rigid or flexible elongated shaft, suitable for insertion into a cavity, having on its tip an endoscope lens to generate an image of a scene in the cavity being observed. To convey the endoscopic image onward from the distal end (that is, away from the observer) of the endoscope to the proximal end (close to the observer), that is, to the operating part, an arranged bundle of light-conducting fibers, for example, or, for rigid endoscopes, a system of rod lenses can be provided inside the shaft; on the proximal end of the endoscope the endoscopic image can be observed directly via an eyepiece or can be recorded by an electronic image recorder for further processing and display. An electronic image recorder, for example a CCD chip, can also be positioned in the area of the distal end of the shaft, that is, at the endoscope tip (“chip on the tip”); in this case, electrical supply and data lines of the image recorder run inside the shaft. Because, as a rule, insufficient light is available in the cavity being observed, a light-conducting system is also provided inside the shaft in order to transport sufficient light to the distal end of the endoscope, where it is used to illuminate the cavity. In addition, channels for endoscopic working instruments as well as, for example, lines for flushing and suction can be fed through the shaft all the way to the distal end of the endoscope shaft. In addition, an endoscope typically includes an operating part that is positioned on the proximal end of the shaft and is usually configured as a handle. Said operating part can, for example, comprise operating elements for controlling the image recorder, an endoscopic video camera and/or junctions for power and data lines, for an external light source and/or for flushing and suction pumps.
Depending on the purpose of the use and the accessibility of the cavity that is to be observed, rigid or flexible endoscopes are used. Here the viewing angle for rigid endoscopes is as a rule determined by the configuration of the object lens. In a number of applications, however, it is desirable to be able to bend the distal end of the endoscope shaft, that is, the endoscope tip, to be able to change not just the alignment of the endoscope tip but also the viewing angle of a lens positioned in the endoscope tip. In flexible endoscopes it is known how to configure a partial area of the shaft, in particular the distal end area of the shaft, so that it is actively bendable and thus can angle the endoscope tip. An area of the cavity can thereby be observed that is far greater than the angle of opening of the observation lens. As a result, better access can be gained to particular areas in the human body that cannot be observed, or can only partly be observed, with a rigid endoscope, areas such as complex-shaped hollow organs like the stomach or digestive tract, as well as the insufflated abdomen during a laparoscopy.
The distal end area of the shaft of a flexible endoscope with bendable tip consists primarily of jointed connected ring elements, which form the supporting structure of the shaft and are operated and tipped toward one another by Bowden cables, also known as curve control wires. To facilitate insertion into the cavity and to prevent penetration by substances, the ring elements are surrounded by a flexible sheath made of a synthetic material. Inside the ring elements, light and image conducting cables are primarily run, along with channels for fluids or endoscopic working instruments. The curve control wires are fed along the outside or inside of the ring elements. Flexible endoscopes of this type are disclosed, for example, in U.S. Pat. No. 6,270,453 B1, U.S. Pat. No. 6,482,149 B1 or DE 101 43 966 B4.
It is also known in the art to bendably configure the distal end area of the shaft with the help of specially shaped bending elements, which can likewise be diverted by Bowden cables, as is described in U.S. Pat. No. 6,749,560 B1 and in EP 1 927 312 A1. It is known from U.S. Pat. No. 5,885,207 A1, U.S. Pat. No. 6,550,193 B1 and U.S. Pat. No. 6,860,849 B2 that the shaft of a flexible endoscope comprises a multi-layered supporting sheath that is made up of various materials with different material characteristic values that combine to form a controllable flexible shaft sheath. Self-resetting springs can also be used in configuring a controllable flexible shaft end, such that the control is likewise exerted by pull wires; endoscopes of this kind are disclosed, for example, in WO 2008/060075 A1 and EP 1 849 400 A1.
Here the minimum radius allowed for the curvable or divertible portion of the shaft is pre-determined by the particular construction principle. For example, a jointed portion made up of ring elements that are arranged one after the other and jointedly connected with one another allows only a relatively large bending radius because the individual ring elements each comprise only a small tipping angle to the next ring element. If the jointed connection of two elements allows only a tipping around one axis, then for a spatial bending capacity it is necessary to arrange elements with tipping axes pivoted alternatingly toward one another so that only each second element can be diverted in a particular desired direction; as a result, the possible minimum bending radius is again enlarged. The area close to the shaft end is therefore not visible with a lens positioned in the endoscope tip.
In the context of the present application, an endoscopic instrument is understood to be one that is suitable for insertion into a cavity and for observation inside the cavity and/or for performing manipulations inside the cavity, although the possibility of optical observation is not necessarily required to be present. Endoscopes for insertion into a cavity and for observation inside the cavity are among the endoscopic instruments in the meaning of the present invention.